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# Page Tags and summary
1 Web APIs API, DOM, JavaScript, Reference, Web
When writing code for the Web with JavaScript, there are a great many APIs available. Below is a list of all the interfaces (that is, types of objects) that you may be able to use while developing your Web app or site.
2 ANGLE_instanced_arrays API, Reference, WebGL, WebGL extension
The ANGLE_instanced_arrays extension is part of the WebGL API and allows to draw the same object, or groups of similar objects multiple times, if they share the same vertex data, primitive count and type.
3 ANGLE_instanced_arrays.drawArraysInstancedANGLE() ANGLE_instanced_arrays, API, Method, Reference, WebGL, WebGL extension
The ANGLE_instanced_arrays.drawArraysInstancedANGLE() method of the WebGL API renders primitives from array data like the gl.drawArrays() method. In addition, it can execute multiple instances of the range of elements.
4 ANGLE_instanced_arrays.drawElementsInstancedANGLE() ANGLE_instanced_arrays, API, Method, Reference, WebGL, WebGL extension
The ANGLE_instanced_arrays.drawElementsInstancedANGLE() method of the WebGL API renders primitives from array data like the gl.drawElements() method. In addition, it can execute multiple instances of a set of elements.
5 ANGLE_instanced_arrays.vertexAttribDivisorANGLE() ANGLE_instanced_arrays, API, Method, Reference, WebGL, WebGL extension
The ANGLE_instanced_arrays.vertexAttribDivisorANGLE() method of the WebGL API  modifies the rate at which generic vertex attributes advance when rendering multiple instances of primitives with ext.drawArraysInstancedANGLE() and ext.drawElementsInstancedANGLE().
6 AbortController API, AbortController, Experimental, Interface, Reference
The AbortController interface represents a controller object that allows you to abort one or more DOM requests as and when desired.
7 AbortController.AbortController() API, AbortController, Constructor, Experimental, Fetch, Reference
The AbortController() constructor creates a new AbortController object instance.
8 AbortController.abort() API, AbortController, Experimental, Fetch, Method, Reference, abort()
The abort() method of the AbortController interface aborts a DOM request (e.g. a Fetch request) before it has completed. This is able to abort fetch requests, consumption of any response Body, and streams.
9 AbortController.signal API, AbortController, Experimental, Fetch, Property, Reference, signal
The signal read-only property of the AbortController interface returns an AbortSignal object instance, which can be used to communicate with/abort a DOM request as desired.
10 AbortSignal API, AbortSignal, DOM, Experimental, Interface, Reference
The AbortSignal interface represents a signal object that allows you to communicate with a DOM request (such as a Fetch) and abort it if required via an AbortController object.
11 AbortSignal.aborted API, AbortSignal, Experimental, Property, Reference, aborted
The aborted read-only property returns a Boolean that indicates whether the DOM request(s) the signal is communicating with is/are aborted (true) or not (false).
12 AbortSignal.onabort API, AbortSignal, Event Handler, Experimental, Fetch, Property, Reference, onabort
The onabort read-only property of the FetchSignal interface is an event handler Invoked when an abort event fires, i.e. when the fetch request(s) the signal is communicating with is/are aborted.
13 AbstractWorker API, AbstractWorker, Interface, Reference, Web Workers
The AbstractWorker interface of the Web Workers API abstracts properties and methods common to all kind of workers, being Worker or SharedWorker.
14 AbstractWorker.onerror API, AbstractWorker, EventHandler, Property, Reference, Web Workers, Workers, onerror
The AbstractWorker.onerror property of the AbstractWorker interface represents an EventHandler, that is a function to be called when the error event occurs and bubbles through the Worker.
15 Ambient Light Events Ambient Light
The ambient light events are a handy way to make a web page or an application aware of any change in the light intensity. It allows them to react to such a change, for example by changing the color contrast of the User Interface (UI) or by changing the exposure necessary to take a picture.
16 Ambient Light Sensor API API, Ambient Light Sensor API, AmbientLightSensor, Landing, Overview, Reference
TBD
17 AmbientLightSensor API, Ambient Light Sensor API, AmbientLightSensor, Interface, Reference
The AmbientLightSensor interface of the the Ambient Light Sensor API returns an interface for accessing AmbientLightSensorReading.
18 AmbientLightSensor.AmbientLightSensor() API, Ambient Light Sensor API, AmbientLightSensor, Constructor, Reference
The AmbinentLightSensor() constructor creates a new AmbientLightSensor object.
19 reading Ambient Light Sensor API, AmbientLightSensor, Property, Reference, reading
The reading read-only property of the AmbientLightSensor interface returns an AmbientLightSensorReading interface, containing the current light level.
20 AmbientLightSensorReading API, Ambient Light Sensor API, AmbientLightSensor, Interface, Reference
The AmbientLightSensorReading interface of the the Ambient Light Sensor API returns an interface for reading the current light level.
21 AmbientLightSensorReading.AmbientLightSensorReading() API, Ambient Light Sensor API, AmbientLightSensor, AmbientLightSensorReading, Constructor, Reference
The AmbientLightSensorReading() constructor creates a new AmbientLightSensorReading object.
22 illuminance API, Ambient Light Level API, AmbientLightSensorReading, Property, Reference, illuminance
The illuminance property of the AmbientLightSensorReading interface returns a Number indicating the current light level.
23 AnalyserNode API, AnalyserNode, Interface, Reference, Web Audio API
The AnalyserNode interface represents a node able to provide real-time frequency and time-domain analysis information. It is an AudioNode that passes the audio stream unchanged from the input to the output, but allows you to take the generated data, process it, and create audio visualizations.
24 AnalyserNode.AnalyserNode() API, AnalyserNode, Audio, Constructor, Media, Reference, Web Audio API
The AnalyserNode constructor of the Web Audio API creates a new AnalyserNode object instance.
25 AnalyserNode.fftSize API, AnalyserNode, Property, Reference, Web Audio API, fftSize
The fftSize property of the AnalyserNode interface is an unsigned long value and represents the window size in samples that is used when performing a Fast Fourier Transform (FFT) to get frequency domain data.
26 AnalyserNode.frequencyBinCount API, AnalyserNode, Property, Reference, Web Audio API, frequencyBinCount
The frequencyBinCount read-only property of the AnalyserNode interface is an unsigned integer half that of the AnalyserNode.fftSize. This generally equates to the number of data values you will have to play with for the visualization.
27 AnalyserNode.getByteFrequencyData() API, AnalyserNode, Method, Reference, Référence(2), Web Audio API
A Uint8Array.
28 AnalyserNode.getByteTimeDomainData() API, AnalyserNode, Method, Reference, Référence(2), Web Audio API
A Uint8Array.
29 AnalyserNode.getFloatFrequencyData() API, AnalyserNode, Method, Reference, Référence(2), Web Audio API
None.
30 AnalyserNode.getFloatTimeDomainData() API, AnalyserNode, Method, Reference, Référence(2), Web Audio API
A Float32Array.
31 AnalyserNode.maxDecibels API, AnalyserNode, Property, Reference, Web Audio API, maxDecibels
The maxDecibels property of the AnalyserNode interface is a double value representing the maximum power value in the scaling range for the FFT analysis data, for conversion to unsigned byte/float values — basically, this specifies the maximum value for the range of results when using getFloatFrequencyData() or getByteFrequencyData().
32 AnalyserNode.minDecibels API, AnalyserNode, Property, Reference, Référence(2), Web Audio API, minDecibels
The minDecibels property of the AnalyserNode interface is a double value representing the minimum power value in the scaling range for the FFT analysis data, for conversion to unsigned byte/float values — basically, this specifies the minimum value for the range of results when using getFloatFrequencyData() or getByteFrequencyData().
33 AnalyserNode.smoothingTimeConstant API, AnalyserNode, Property, Reference, Référence(2), Web Audio API, smoothingTimeConstant
The smoothingTimeConstant property of the AnalyserNode interface is a double value representing the averaging constant with the last analysis frame. It's basically an average
between the current buffer and the last buffer the AnalyserNode processed, and results in a much smoother set of value changes over time.
34 Animation API, Animations, Experimental, Interface, Reference, Web Animations, waapi, web animation api
The Animation interface of the Web Animations API represents a single animation player and provides playback controls and a timeline for an animation node or source.
35 Animation() API, Animation, Animations, Constructor, Experimental, Reference, web animations api
The Animation() constructor of the Web Animations API returns a new Animation object instance.
36 Animation.cancel() API, Animation, Method, Reference, Web Animations, cancel, waapi, web animations api
The Web Animations API's cancel() method of the Animation interface clears all KeyframeEffects caused by this animation and aborts its playback.
37 Animation.currentTime API, Animation, Animations, Property, Reference, Web Animations, web animations api
The Animation.currentTime property of the Web Animations API returns and sets the current time value of the animation in milliseconds, whether running or paused.
38 Animation.effect API, Animation, Experimental, Property, Reference, Web Animations, effect, web animations api
The Animation.effect property of the Web Animations API gets and sets the target effect of an animation. The target effect may be either an effect object of a type based on AnimationEffectReadOnly, such as KeyframeEffect, or null.
39 Animation.finish() API, Animation, Finish, Interface, Method, Reference, Web Animations, waapi, web animations api
The finish() method of the Web Animations API's Animation Interface sets the current playback time to the end of the animation corresponding to the current playback direction.
40 Animation.finished API, Animation, Experimental, Property, Reference, Web Animations, finished, web animations api
The Animation.finished read-only property of the Web Animations API returns a Promise which resolves once the animation has finished playing.
41 Animation.id API, Animation, Property, Reference, id, web animations api
The Animation.id property of the Web Animations API returns or sets a string used to identify the animation.
42 Animation.oncancel API, Animation, Event Handler, Property, Reference, Web Animations, events, oncancel, web animations api
The oncancel property of the Web Animations API's Animation interface is the event handler for the cancel event.
43 Animation.onfinish API, Animation, Event Handler, Property, Reference, Web Animations, events, onfinish, waapi, web animations api
The Animation interface's onfinish property (from the Web Animations API) is the event handler for the finish event. This event is sent when the animation finishes playing.
44 Animation.pause() Animation, Method, Reference, Web Animations, pause, waapi, web animations api
The pause() method of the Web Animations API's Animation interface suspends playback of the animation.
45 Animation.pending API, Animation, Animations, Property, Reference, Web Animations, web animations api
The read-only Animation.pending property of the Web Animations API indicates whether the animation is currently waiting for an asynchronous operation such as initiating playback or pausing a running animation.
46 Animation.play() API, Animation, Interface, Method, Reference, Web Animations, play, waapi, web animations api
The play() method of the Web Animations API's Animation Interface starts or resumes playing of an animation. If the animation is finished, calling play() restarts the animation, playing it from the beginning.
47 Animation.playState API, Animation, Property, Reference, Web Animations, playState, web animations api
The Animation.playState property of the Web Animations API returns and sets an enumerated value describing the playback state of an animation.
48 Animation.playbackRate API, Animation, Interface, Property, Reference, Web Animations, playbackRate, web animations api
The Animation.playbackRate property of the Web Animations API returns or sets the playback rate of the animation.
49 Animation.ready API, Animation, Experimental, Property, Ready, Ready Promise, Reference, Web Animations, web animations api
The read-only Animation.ready property of the Web Animations API returns a Promise which resolves when the animation is ready to play. A new promise is created every time the animation enters the "pending" play state as well as when the animation is canceled, since in both of those scenarios, the animation is ready to be started again.
50 Animation.reverse() API, Animation, Interface, Method, Reference, Web Animations, reverse, waapi, web animations api
The Animation.reverse() method of the Animation Interface reverses the playback direction, meaning the animation ends at its beginning. If called on an unplayed animation, the whole animation is played backwards. If called on a paused animation, the animation will continue in reverse.
51 Animation.startTime API, Animation, Interface, Property, Reference, Web Animations, startTime, web animations api
The Animation.startTime property of the Animation interface is a double-precision floating-point value which indicates the scheduled time when an animation's playback should begin.
52 Animation.timeline API, Animation, Experimental, Property, Reference, Web Animations, timeline, web animations api
The Animation.timeline property of the Animation interface returns or sets the timeline associated with this animation. A timeline is a source of time values for synchronization purposes, and is an AnimationTimeline-based object. By default, the animation's timeline and the Document's timeline are the same.
53 Animation.updatePlaybackRate() API, Animation, Experimental, Interface, Method, Reference, Web Animations, playbackRate, updatePlaybackRate, waapi, web animations api
The updatePlaybackRate() method of the Web Animations API's Animation Interface sets the speed of an animation after first synchronizing its playback position.
54 AnimationEffectReadOnly API, Animation, AnimationEffectReadOnly, Experimental, Interface, Reference, web animations api
The AnimationEffectReadOnly interface of the Web Animations API defines current and future animation effects like KeyframeEffect, which can be passed to Animation objects for playing, and KeyframeEffectReadOnly (which is used by CSS Animations and Transitions).
55 AnimationEffectReadOnly.getComputedTiming() API, Animation, AnimationEffectReadOnly, Experimental, Method, Reference, getComputedTiming, waapi, web animations api
The getComputedTiming() method of the AnimationEffectReadOnly interface returns the calculated timing properties for this animation effect.
56 AnimationEffectReadOnly.timing API, Animation, AnimationEffectReadOnly, Attribute, Experimental, Property, Reference, Timing, waapi, web animations api
The AnimationEffectReadOnly.timing read-only attribute of the AnimationEffectReadOnly interface returns an AnimationEffectTimingReadOnly object containing the timing properties for the Animation Effect.
57 AnimationEffectTiming API, Animation, AnimationEffectTiming, AnimationEffectTimingReadOnly, Experimental, Interface, Reference, web animations api
The AnimationEffectTiming interface of the Web Animations API is comprised of timing properties. It is returned by the timing attribute of a KeyframeEffect.
58 AnimationEffectTimingProperties API, Animation, AnimationEffectTimingProperties, Dictionary, Experimental, Interface, KeyframeEffect, KeyframeEffectReadOnly, Reference, Web Animations, animate, web animations api
The AnimationEffectTimingProperties dictionary, part of the Web Animations API, is used by Element.animate(), KeyframeEffectReadOnly(), and KeyframeEffect() to describe timing properties for animation effects. These properties are all optional, although without setting a duration the animation will not play.
59 AnimationEffectTimingProperties.delay API, Animation, AnimationEffectTimingProperties, Experimental, KeyframeEffect, KeyframeEffectReadOnly, Property, Reference, Web Animations, animate, delay, waapi, web animations api
The AnimationEffectTimingProperties dictionary's delay property in the Web Animations API represents the number of milliseconds to delay the start of the animation.
60 AnimationEffectTimingProperties.direction API, Animation, AnimationEffectTimingProperties, AnimationEffectTimingReadOnly, Experimental, KeyframeEffect, KeyframeEffectReadOnly, Property, Reference, Web Animations, animate, direction, waapi, web animations api
The direction property of the Web Animations API dictionary AnimationEffectTimingProperties indicates an animation's playback direction along its timeline, as well as its behavior when it reaches the end of an interation
61 AnimationEffectTimingProperties.duration API, Animation, AnimationEffectTimingProperties, AnimationEffectTimingReadOnly, Experimental, KeyframeEffect, KeyframeEffectReadOnly, Property, Reference, Web Animations, animate, duration, waapi, web animations api
The duration property of the dictionary AnimationEffectTimingProperties in the Web Animations API specifies the duration in milliseconds that a single iteration (from beginning to end) the animation should take to complete.
62 AnimationEffectTimingProperties.easing API, Animation, AnimationEffectTimingProperties, AnimationEffectTimingReadOnly, Experimental, KeyframeEffect, KeyframeEffectReadOnly, Property, Reference, Timing Function, Web Animations, animate, easing, waapi, web animations api
The {domxref("AnimationEffectTimingProperties")}} dictionary's easing property in the Web Animations API specifies the timing function used to scale the time to produce easing effects, where easing is the rate of the animation's change over time.
63 AnimationEffectTimingProperties.endDelay API, Animation, AnimationEffectTimingProperties, AnimationEffectTimingReadOnly, Experimental, KeyframeEffect, KeyframeEffectReadOnly, Property, Reference, Web Animations, animate, endDelay, waapi, web animations api
The endDelay property of the AnimationEffectTimingProperties dictionary (part of the Web Animations API) indicates the number of milliseconds to delay after the active period of an animation sequence. The animation's end time—the time at which an iteration is considered to have finished—is the time at which the animation finishes an iteration (its initial delay, AnimationEffectTimingReadOnly.delay, plus its duration,duration, plus its end delay.
64 AnimationEffectTimingProperties.fill API, Animation, AnimationEffectTimingProperties, AnimationEffectTimingReadOnly, Experimental, KeyframeEffect, KeyframeEffectReadOnly, Property, Reference, Web Animations, animate, fill, web animations api
The Web Animations API's AnimationEffectTimingProperties dictionary's fill property specifies a fill mode, which defines how the element to which the animation is applied should look when the animation sequence is not actively running, such as before the time specified by iterationStart or after animation's end time.
65 AnimationEffectTimingProperties.iterationStart API, Animation, Animation Timing Properties, AnimationEffectTimingReadOnly, Experimental, KeyframeEffect, KeyframeEffectReadOnly, Property, Reference, Web Animations, animate, iterationStart, waapi, web animations api
Web Animations API's AnimationEffectTimingProperties dictionary's  iterationStart property specifies the repetition number which repetition the animation begins at and its progress through it.
66 AnimationEffectTimingProperties.iterations API, Animation, AnimationEffectTimingProperties, AnimationEffectTimingReadOnly, Experimental, KeyframeEffect, KeyframeEffectReadOnly, Property, Reference, Web Animations, animate, iterations, waapi, web animations api
The Web Animations API dictionary AnimationEffectTimingProperties's iterations property specifies the number of times the animation should repeat. The default value is 1, indicating that it should only play once, but you can set it to any floating-point value (including positive Infinity defaults to 1, and can also take a value of Infinity to make it loop infinitely.
67 AnimationEffectTimingReadOnly API, Animation, AnimationEffectTimingReadOnly, Experimental, Interface, Reference, waapi, web animations api
The AnimationEffectTimingReadOnly interface of the Web Animations API is comprised of timing properties.
68 AnimationEffectTimingReadOnly.delay API, Animation, AnimationEffectTimingReadOnly, Experimental, Property, Reference, delay, waapi, web animations api
The delay property of the AnimationEffectTimingReadOnly object represents the number of milliseconds to delay the start of the animation.
69 AnimationEffectTimingReadOnly.direction API, Animation, AnimationEffectTimingReadOnly, Experimental, Property, Reference, direction, waapi, web animations api
The direction property of the AnimationEffectTimingReadOnly dictionary object represents the direction of the animation's playback along its timeline and its behavior after completing each iteration.
70 AnimationEffectTimingReadOnly.duration API, Animation, AnimationEffectTimingReadOnly, Experimental, Property, Reference, duration, waapi, web animations api
The duration property of AnimationEffectTimingReadOnly represents the duration in milliseconds to complete a single iteration of the animation.
71 AnimationEffectTimingReadOnly.easing API, Animation, AnimationEffectTimingReadOnly, Experimental, Property, Reference, easing, web animations api
The easing property of the AnimationEffectTimingReadOnly object represents the timing function used to scale the time to produce easing effects. Easing is the rate of the animation's change over time.
72 AnimationEffectTimingReadOnly.endDelay API, Animation, AnimationEffectTimingReadOnly, Experimental, Property, Reference, endDelay, waapi, web animations api
The endDelay property of AnimationEffectTimingReadOnly represents the number of milliseconds to delay after the end time of an animation. The end time of an animation effect is simply the sum of its delay, duration, and endDelay.
73 AnimationEffectTimingReadOnly.fill API, Animation, AnimationTimingEffectReadOnly, Experimental, Property, Reference, fill, waapi, web animations api
The fill property of AnimationEffectTimingReadOnly dictates how and when the animation's effects should be reflected by the element(s) visual state.
74 AnimationEffectTimingReadOnly.iterationStart API, Animation, AnimationEffectTimingReadOnly, Experimental, Property, Reference, waapi, web animations api
The iterationStart property of AnimationEffectTimingReadOnly represents which repetition the animation begins at and its progress through it.
75 AnimationEffectTimingReadOnly.iterations API, Animation, AnimationEffectTimingReadOnly, Experimental, Property, Reference, iterations, waapi, web animations api
The iterations property of AnimationEffectTimingReadOnly represents the number of times the animation should repeat. It defaults to 1, and can also take a value of Infinity to make it loop infinitely.
76 AnimationEvent API, Experimental, Interface, Reference, Web Animations
The AnimationEvent interface represents events providing information related to animations.
77 AnimationEvent() API, AnimationEvent, CSSOM, Constructor, Experimental, Expérimental(2), Reference, Référence(2), Web Animations
The AnimationEvent() constructor returns a newly created AnimationEvent, representing an event in relation with an animation.
78 AnimationEvent.animationName API, AnimationEvent, CSSOM, Experimental, Property, Reference, Web Animations
The AnimationEvent.animationName read-only property is a DOMString containing the value of the animation-name CSS property associated with the transition.
79 AnimationEvent.elapsedTime API, AnimationEvent, CSSOM, Experimental, Property, Reference, Web Animations
The AnimationEvent.elapsedTime read-only property is a float giving the amount of time the animation has been running, in seconds, when this event fired, excluding any time the animation was paused. For an "animationstart" event, elapsedTime is 0.0 unless there was a negative value for animation-delay, in which case the event will be fired with elapsedTime containing  (-1 * delay).
80 AnimationEvent.initAnimationEvent() API, AnimationEvent, CSSOM, Method, Obsolete, Web Animations
The AnimationEvent.initAnimationEvent() method Initializes an animation event created using the deprecated Document.createEvent("AnimationEvent") method.
81 AnimationEvent.pseudoElement API, AnimationEvent, CSS, CSSOM, Experimental, Property, Reference, Web Animations
The AnimationEvent.pseudoElement read-only property is a DOMString, starting with '::', containing the name of the pseudo-element the animation runs on. If the animation doesn't run on a pseudo-element but on the element, an empty string: ''.
82 AnimationPlaybackEvent API, Animation, AnimationPlaybackEvent, Experimental, Interface, Reference, events, waapi, web animations api
The AnimationPlaybackEvent interface of the Web Animations API represents animation events.
83 AnimationPlaybackEvent.AnimationPlaybackEvent() API, Animation, AnimationPlaybackEvent, AnimationPlaybackEvent(), Constructor, Experimental, Reference, waapi, web animations api
The AnimationPlaybackEvent() constructor of the Web Animations API returns a new AnimationPlaybackEvent object instance.
84 AnimationPlaybackEvent.currentTime API, Animation, AnimationPlaybackEvent, Attribute, Experimental, Property, Reference, currentTime, waapi, web animations api
The currentTime read-only property of the AnimationPlaybackEvent interface represents the current time of the animation that generated the event at the moment the event is queued. This will be unresolved if the animation was idle at the time the event was generated.
85 AnimationPlaybackEvent.timelineTime API, Animation, AnimationPlaybackEvent, Attribute, Experimental, Property, Reference, timelineTime, waapi, web animations api
The timelineTime read-only property of the AnimationPlaybackEvent interface represents the time value of the animation's timeline at the moment the event is queued. This will be unresolved if the animation was not associated with a timeline at the time the event was generated or if the associated timeline was inactive.
86 AnimationTimeline API, Animation, AnimationTimeline, Experimental, Interface, Reference, Web Animations, waapi, web animations api
The AnimationTimeline interface of the Web Animations API represents the timeline of an animation. This interface exists to define timeline features (inherited by DocumentTimeline and future timeline types) and is not itself directly used by developers. Anywhere you see AnimationTimeline, you should use DocumentTimeline or any other timeline type instead.
87 AnimationTimeline.currentTime API, Animation, AnimationTimeline, Experimental, Property, Read-only, Reference, Web Animations, currentTime, waapi, web animations api
The currentTime read-only property of the Web Animations API's AnimationTimeline interface returns the timeline's current time in milliseconds, or null if the timeline is inactive.
88 ArrayBufferView API, Interface, JavaScript, Reference, Référence(2), Typed Arrays
ArrayBufferView is a helper type representing any of the following JavaScript TypedArray types:
89 Attr API, DOM, NeedsBrowserCompatibility
This type represents a DOM element's attribute as an object. In most DOM methods, you will probably directly retrieve the attribute as a string (e.g., Element.getAttribute(), but certain functions (e.g., Element.getAttributeNode()) or means of iterating give Attr types.
90 Attr.localName API, DOM, NeedsBrowserCompatibility, NeedsMobileBrowserCompatibility, Property, Reference
The Attr.localName read-only property returns the local part of the qualified name of an element.
91 Attr.namespaceURI API, DOM, NeedsBrowserCompatibility, NeedsMobileBrowserCompatibility, Property, Reference
The Attr.namespaceURI read-only property returns the namespace URI of the attribute, or null if the element is not in a namespace.
92 Attr.prefix API, DOM, NeedsBrowserCompatibility, NeedsMobileBrowserCompatibility, Property, Reference
The Attr.prefix read-only property returns the namespace prefix of the specified attribute, or null if no prefix is specified.
93 AudioBuffer API, AudioBuffer, Interface, Reference, Référence(2), Web Audio API
Objects of these types are designed to hold small audio snippets, typically less than 45 s. For longer sounds, objects implementing the MediaElementAudioSourceNode are more suitable. The buffer contains data in the following format:  non-interleaved IEEE754 32-bit linear PCM with a nominal range between -1 and +1, that is, 32bits floating point buffer, with each samples between -1.0 and 1.0. If the AudioBuffer has multiple channels, they are stored in separate buffer.
94 AudioBuffer() API, Audio, AudioBuffer, Constructor, Media, Reference, Web Audio API
The AudioBuffer constructor of the Web Audio API creates a new AudioBuffer object.
95 AudioBuffer.copyFromChannel() API, AudioBuffer, Method, Reference, Référence(2), Web Audio API, copyFromChannel
The copyFromChannel() method of the AudioBuffer interface copies the samples from the specified channel of the AudioBuffer to the destination array.
96 AudioBuffer.copyToChannel() API, Audio, AudioBuffer, Method, Reference, Web Audio API, copyToChannel
The copyToChannel() method of the AudioBuffer interface copies the samples to the specified channel of the AudioBuffer, from the source array.
97 AudioBuffer.duration API, AudioBuffer, Property, Reference, Référence(2), Web Audio API, duration
A double.
98 AudioBuffer.getChannelData() API, AudioBuffer, Method, Reference, Référence(2), Web Audio API
A Float32Array.
99 AudioBuffer.length API, AudioBuffer, Property, Reference, Référence(2), Web Audio API, length
A float.
100 AudioBuffer.numberOfChannels API, AudioBuffer, Property, Reference, Référence(2), Web Audio API, numberOfChannels
An integer.
101 AudioBuffer.sampleRate API, AudioBuffer, Property, Reference, Référence(2), Web Audio API, sampleRate
A floating-point value indicating the current smaple rate of the buffer's data, in samples per second.
102 AudioBufferSourceNode API, Audio, AudioBufferSourceNode, Interface, Media, Reference, Web Audio API
The AudioBufferSourceNode interface is an AudioScheduledSourceNode which represents an audio source consisting of in-memory audio data, stored in an AudioBuffer. It's especially useful for playing back audio which has particularly stringent timing accuracy requirements, such as for sounds that must match a specific rhythm and can be kept in memory rather than being played from disk or the network.
103 AudioBufferSourceNode.AudioBufferSourceNode() API, Audio, AudioBufferSourceNode, Constructor, Media, Reference, Web Audio API
The AudioBufferSourceNode() constructor creates a new AudioBufferSourceNode object instance.
104 AudioBufferSourceNode.buffer API, Audio, AudioBufferSourceNode, Buffer, Media, Property, Reference, Web Audio API, sound
The buffer property of the AudioBufferSourceNode interface provides the ability to play back audio using an AudioBuffer as the source of the sound data.
105 AudioBufferSourceNode.detune API, AudioBufferSourceNode, Property, Reference, Web Audio API, detune
The detune property of the AudioBufferSourceNode interface is an k-rate AudioParam representing detuning of oscillation in cents.
106 AudioBufferSourceNode.loop API, Audio, AudioBufferSourceNode, Loop, Media, Property, Reference, Web Audio API, sound
The loop property's default value is false.
107 AudioBufferSourceNode.loopEnd API, Audio, AudioBufferSourceNode, Media, Property, Reference, Web Audio API, loopEnd, sound
A floating-point number indicating the offset, in seconds, into the audio buffer at which each loop will loop return to the beginning of the loop (that is, the current play time gets reset to AudioBufferSourceNode.loopStart). This property is only used if the loop property is true.
108 AudioBufferSourceNode.loopStart API, Audio, AudioBufferSourceNode, Media, Property, Reference, Web Audio API, loopStart, sound
The loopStart property's default value is 0.
109 AudioBufferSourceNode.playbackRate API, AudioBufferSourceNode, Property, Reference, Référence(2), Web Audio API, playbackRate
The playbackRate property of the AudioBufferSourceNode interface Is a k-rate AudioParam that defines the speed at which the audio asset will be played.
110 AudioBufferSourceNode.start() API, Audio, AudioBufferSourceNode, Media, Method, Reference, Web Audio API, sound, start
undefined.
111 AudioContext API, Audio, AudioContext, Interface, Reference, Web Audio API, sound
The AudioContext interface represents an audio-processing graph built from audio modules linked together, each represented by an AudioNode. An audio context controls both the creation of the nodes it contains and the execution of the audio processing, or decoding. You need to create an AudioContext before you do anything else, as everything happens inside a context.
112 AudioContext() Audio, AudioContext, Constructor, Media, Web Audio API
The AudioContext() constructor creates a new AudioContext object which represents an audio-processing graph, built from audio modules linked together, each represented by an AudioNode.
113 AudioContext.baseLatency API, Audio, AudioContext, Experimental, Media, Property, Web Audio API, baseLatency
The baseLatency read-only property of the AudioContext interface returns a double that represents the number of seconds of processing latency incurred by the AudioContext passing the audio from the AudioDestinationNode to the audio subsystem.
114 AudioContext.close() API, AudioContext, Media, Method, Reference, Web Audio API, close
The close() method of the AudioContext Interface closes the audio context, releasing any system audio resources that it uses.
115 AudioContext.createJavaScriptNode() API, Audio, Method, Obsolete, Reference, Web, createJavaScriptNode
The following script illustrates the use of createJavaScriptNode():
116 AudioContext.createMediaElementSource() API, AudioContext, Method, Reference, Référence(2), Web Audio API, createMediaElementSource
For more details about media element audio source nodes, check out the MediaElementAudioSourceNode reference page.
117 AudioContext.createMediaStreamDestination() API, AudioContext, Method, Reference, Référence(2), Web Audio API, createMediaStreamDestination
The MediaStream is created when the node is created and is accessible via the MediaStreamAudioDestinationNode's stream attribute. This stream can be used in a similar way as a MediaStream obtained via navigator.getUserMedia — it can, for example, be sent to a remote peer using the RTCPeerConnection addStream() method.
118 AudioContext.createMediaStreamSource() API, Audio, AudioContext, Method, Reference, Web Audio API, createMediastreamSource
For more details about media stream audio source nodes, check out the MediaStreamAudioSourceNode reference page.
119 AudioContext.createMediaStreamTrackSource() API, Audio, AudioContext, Method, Reference, Web Audio API, createMediaStreamTrackSource
A MediaStreamTrackAudioSourceNode.
120 AudioContext.createWaveTable() API, AudioContext, Method, Obsolete, Reference, Web Audio API, createWaveTable
The AudioContext method createWaveTable() is now obsolete; you should instead use the method createPeriodicWave().
121 AudioContext.getOutputTimestamp() API, Audio, AudioContext, Method, Reference, Web Audio API, getOutputTimestamp, sound
The getOutputTimestamp() property of the AudioContext interface returns a new AudioTimestamp object containing two correlated context's audio stream position values.
122 AudioContext.outputLatency API, Audio, AudioContext, Experimental, Property, Reference, Web Audio API, outputLatency
The outputLatency read-only property of the AudioContext Interface provides an estimation of the output latency of the current audio context.
123 AudioContext.suspend() API, Audio, AudioContext, Method, Reference, Web Audio API, suspend
The suspend() method of the AudioContext Interface suspends the progression of time in the audio context, temporarily halting audio hardware access and reducing CPU/battery usage in the process — this is useful if you want an application to power down the audio hardware when it will not be using an audio context for a while.
124 AudioDestinationNode API, AudioDestinationNode, Interface, Reference, Web Audio API
AudioDestinationNode has no output (as it is the output, no more AudioNode can be linked after it in the audio graph) and one input. The number of channels in the input must be between 0 and the maxChannelCount value or an exception is raised.
125 AudioDestinationNode.maxChannelCount API, AudioDestinationNode, Property, Reference, Référence(2), Web Audio API, maxChannelCount
An unsigned long.
126 AudioListener API, AudioListener, Interface, Reference, Référence(2), Web Audio API
It is important to note that there is only one listener per context and that it isn't an AudioNode.
127 AudioListener.dopplerFactor API, AudioListener, Deprecated, Property, Reference, Web Audio API, dopplerFactor
A double.
128 AudioListener.forwardX API, Audio, AudioListener, Property, Reference, Web Audio API, forwardX
The forwardX read-only property of the AudioListener interface is an AudioParam representing the x value of the direction vector defining the forward direction the listener is pointing in.
129 AudioListener.forwardY API, Audio, AudioListener, Property, Reference, Web Audio API, forwardY
The forwardY read-only property of the AudioListener interface is an AudioParam representing the y value of the direction vector defining the forward direction the listener is pointing in.
130 AudioListener.forwardZ API, Audio, AudioListener, Property, Reference, Web Audio API, forwardZ
The forwardZ read-only property of the AudioListener interface is an AudioParam representing the z value of the direction vector defining the forward direction the listener is pointing in.
131 AudioListener.positionX API, Audio, AudioListener, Property, Reference, Web Audio API, positionX
The positionX read-only property of the AudioListener interface is an AudioParam representing the x position of the listener in 3D cartesian space.
132 AudioListener.positionY API, Audio, AudioListener, Property, Reference, Web Audio API, positionY
The positionY read-only property of the AudioListener interface is an AudioParam representing the y position of the listener in 3D cartesian space.
133 AudioListener.positionZ API, Audio, AudioListener, Property, Reference, Web Audio API, positionZ
The positionZ read-only property of the AudioListener interface is an AudioParam representing the z position of the listener in 3D cartesian space.
134 AudioListener.setOrientation() API, AudioListener, Method, Reference, Référence(2), Web Audio API, setOrientation
Void.
135 AudioListener.setPosition() API, AudioListener, Deprecated, Method, Reference, Référence(2), Web Audio API, setPosition
Void.
136 AudioListener.speedOfSound API, AudioListener, Deprecated, Property, Reference, Référence(2), Web Audio API, speedOfSound
The speedOfSound property of the AudioListener interface is a double value representing the speed of sound, in meters per second.
137 AudioListener.upX API, Audio, AudioListener, Property, Reference, Web Audio API, upX
The upX read-only property of the AudioListener interface is an AudioParam representing the x value of the direction vector defining the up direction the listener is pointing in.
138 AudioListener.upY API, AudioListener, Property, Reference, Web Audio API, upY
The upY read-only property of the AudioListener interface is an AudioParam representing the y value of the direction vector defining the up direction the listener is pointing in.
139 AudioListener.upZ API, Audio, AudioListener, Property, Reference, Web Audio API, upZ
The upZ read-only property of the AudioListener interface is an AudioParam representing the z value of the direction vector defining the up direction the listener is pointing in.
140 AudioNode API, AudioNode, Interface, Reference, Référence(2), Web Audio API
The AudioNode interface is a generic interface for representing an audio processing module. Examples include:
141 AudioNode.channelCount API, AudioNode, Property, Reference, Référence(2), Web Audio API, channelCount
channelCount's usage and precise definition depend on the value of AudioNode.channelCountMode:
142 AudioNode.channelCountMode API, AudioNode, Property, Reference, Web Audio API, channelCountMode
The possible values of channelCountMode and their meanings are:
143 AudioNode.channelInterpretation API, AudioNode, Property, Reference, Référence(2), Web Audio API, channelInterpretation
When the number of channels doesn't match between an input and an output, up- or down-mixing happens according the following rules. This can be somewhat controlled by setting the AudioNode.channelInterpretation property to speakers or discrete:
144 AudioNode.connect() API, Audio, AudioNode, Media, Method, Reference, Web Audio API, connect
If the destination is a node, connect() returns a reference to the destination AudioNode object, allowing you to chain multiple connect() calls. In some browsers, older implementations of this interface return undefined.
145 AudioNode.context API, AudioNode, Context, Property, Reference, Web Audio API
The read-only context property of the AudioNode interface returns the associated BaseAudioContext, that is the object representing the processing graph the node is participating in.
146 AudioNode.disconnect() API, Audio, AudioNode, Disconnect, Method, Reference, Web Audio API
undefined
147 AudioNode.numberOfInputs API, AudioNode, Property, Reference, Web Audio API, numberOfInputs
The numberOfInputs property of the AudioNode interface returns the number of inputs feeding the node.
148 AudioNode.numberOfOutputs API, AudioNode, Property, Reference, Web Audio API, numberOfOutputs
The numberOfOutputs property of the AudioNode interface returns the number of outputs coming out of the node.
149 AudioNodeOptions API, Audio, AudioNodeOptions, Dictionary, Reference, Web Audio API
The AudioNodeOptions dictionary of the Web Audio API specifies options that can be used when creating new AudioNode objects.
150 AudioParam API, Audio, AudioParam, Interface, Reference, Web Audio API
There are two kinds of AudioParam, a-rate and k-rate parameters:
151 AudioParam.cancelAndHoldAtTime() API, Audio, AudioParam, Experimental, Method, Reference, Web Audio API, cancelAndHoldAtTime, cancelValuesAndHoldAtTime
The cancelAndHoldAtTime() property of the AudioParam interface cancels all scheduled future changes to the AudioParam but holds its value at a given time until further changes are made using other methods. The new value is given in the value parameter.
152 AudioParam.cancelScheduledValues() API, AudioParam, Method, Reference, Web Audio API, cancelScheduledValues
A reference to this AudioParam object. In some older implementations this method returns void.
153 AudioParam.defaultValue API, AudioParam, Property, Reference, Référence(2), Web Audio API, defaultValue
The defaultValue read-only property of the AudioParam interface represents the initial value of the attributes as defined by the specific AudioNode creating the AudioParam.
154 AudioParam.exponentialRampToValueAtTime() API, AudioParam, Method, Reference, Web Audio API, exponentialRampToValueAtTime
A reference to this AudioParam object. In some browsers older implementations of this interface return void.
155 AudioParam.linearRampToValueAtTime() API, Audio, AudioParam, Method, Reference, Web Audio API, linearRampToValueAtTime
NOTE: both the example and live example are incorrect, see https://github.com/WebAudio/web-audio-api/issues/341
156 AudioParam.maxValue API, Audio, AudioParam, Property, Reference, Web Audio API, maxValue
The maxValue read-only property of the AudioParam interface represents the maximum possible value for the parameter's nominal (effective) range.
157 AudioParam.minValue API, Audio, AudioParam, Property, Reference, Web Audio API, minValue
The minValue read-only property of the AudioParam interface represents the minimum possible value for the parameter's nominal (effective) range.
158 AudioParam.setTargetAtTime() API, AudioParam, Method, Reference, Web Audio API, setTargetAtTime
The setTargetAtTime() method of the AudioParam interface schedules the start of a gradual change to the AudioParam value. This is useful for decay or release portions of ADSR envelopes.
159 AudioParam.setValueAtTime() API, AudioParam, Method, Reference, Web Audio API, setValueAtTime
The setValueAtTime() method of the AudioParam interface schedules an instant change to the AudioParam value at a precise time, as measured against AudioContext.currentTime. The new value is given in the value parameter.
160 AudioParam.setValueCurveAtTime() API, Audio, AudioParam, Method, Reference, Web, Web Audio, Web Audio API, setValueCurveAtTime
The setValueCurveAtTime() method of the AudioParam interface schedules the start of a linear interpolation between the sequence of values defined in a Float32Array, which are scaled to fit into the given interval starting at startTime and having a specific duration.
161 AudioParam.value API, AudioParam, Property, Reference, Web Audio API, value
Gets or sets the current value of this AudioParam. Initially, the value is set to AudioParam.defaultValue. Part of the Web Audio API.
162 AudioProcessingEvent API, Deprecated, Interface, Internationalization, Reference, Référence(2), Web Audio API
The Web Audio API AudioProcessingEvent represents events that occur when a ScriptProcessorNode input buffer is ready to be processed.
163 AudioScheduledSourceNode API, Audio, AudioScheduledSourceNode, Interface, Media, Reference, Web Audio API, sound
The AudioScheduledSourceNode interface—part of the Web Audio API—is a parent interface for several types of audio source node interfaces which share the ability to be started and stopped, optionally at specified times. Specifically, this interface defines the start() and stop() methods, as well as the onended event handler.
164 AudioScheduledSourceNode.onended API, Audio, AudioBufferSourceNode, AudioScheduledSourceNode, ConstantSourceNode, Event Handler, Media, OscillatorNode, Property, Web Audio API, onended
The onended event handler for the AudioScheduledSourceNode interface specifies an EventHandler to be executed when the ended event occurs on the node. This event is sent to the node when the concrete interface (such as AudioBufferSourceNode, OscillatorNode, or ConstantSourceNode) determines that it has stopped playing.
165 AudioScheduledSourceNode.start() API, Audio, AudioScheduledSoundNOde, Media, Method, Node, Reference, Web Audio API, play, sound, start
undefined
166 AudioScheduledSourceNode.stop() API, Audio, AudioScheduledSourceNode, Media, Method, Reference, Web Audio API, sound, stop
The stop() method on AudioScheduledSourceNode schedules a sound to cease playback at the specified time. If no time is specified, then the sound stops playing immediately.
167 AuthenticatorAssertionResponse
When a WebAuthn authenticator peforms an authentication via the get() call, the result is a new PublicKeyCredential, the PublicKeyCredential.response value will be an AuthenticatorAssertionResponse object. This object contains both the client data (i.e. - browser data) for the authentication as well as the data from the authenticator to cryptographically prove that the authentication is valid.
168 AuthenticatorAttestationResponse
{{APIRef("Web Authentication API")}}{{ SeeCompatTable() }}
169 attestationObject
As part of the WebAuthn create() call, an authenticator will create a new keypair as well as an attestationObject for that keypair. The attestationObject contains the new public key, as well as signature over the entire attestationObject with a private key that is stored in the authenticator when it is manufactured. The public key that corresponds to the private key that has created the attestation signature is well known; however, there are various well known attestation public key chains for different ecosystems (for example, Android or TPM attestations).
170 AuthenticatorResponse
This is the base interface of AuthenticatorAttestationResponse and AuthenticatorAssertionResponse, which are part of the PublicKeyCredential.response resulting from create() and get(), respectively. It contains the AuthenticatorResponse.clientDataJSON that is inherited by those interfaces.
171 clientDataJSON
The clientDataJSON object is an ArrayBuffer containing a JSON String of the various browser data that was used for the WebAuthn create() or get() call. It is included in both an AuthenticatorAttestationResponse and an AuthenticatorAssertionResponse within a PublicKeyCredential. The reason for storing the data as a ArrayBuffer rather than a String or an actual JavaScript object is that the object is effectively signed over by the authenticator, and if the order of the properties of the JavaScript object were not preserved then the signature verification would fail.
172 BaseAudioContext API, Audio, BaseAudioContext, Interface, Reference, Web Audio API
The BaseAudioContext interface acts as a base definition for online and offline audio-processing graphs, as represented by AudioContext and OfflineAudioContext respectively.
173 BaseAudioContext.createAnalyser() API, AudioContext, BaseAudioContext, Method, Reference, Web Audio API, createAnalyser
The createAnalyser() method of the BaseAudioContext interface creates an AnalyserNode, which can be used to expose audio time and frequency data and create data visualisations.
174 BaseAudioContext.createBiquadFilter() API, AudioContext, BaseAudioContext, Method, Reference, Web Audio API, createBiquadFilter
A BiquadFilterNode.
175 BaseAudioContext.createBuffer() API, AudioContext, BaseAudioContext, Method, Reference, Web Audio API, createBuffer
An AudioBuffer.
176 BaseAudioContext.createBufferSource() API, AudioContext, BaseAudioContext, Method, Reference, Web Audio API, createBufferSource
An AudioBufferSourceNode.
177 BaseAudioContext.createChannelMerger() API, Audio, AudioContext, BaseAudioContext, Method, Reference, Web Audio API, createChannelMerger
A ChannelMergerNode.
178 BaseAudioContext.createChannelSplitter() API, AudioContext, BaseAudioContext, Method, Reference, Web Audio API, createChannelSplitter
A ChannelSplitterNode.
179 BaseAudioContext.createConstantSource() API, Audio, AudioContext, BaseAudioContext, ConstantSourceNode, Media, Method, createConstantSource
The createConstantSource() property of the BaseAudioContext interface creates a ConstantSourceNode object, which is an audio source that continuously outputs a monaural (one-channel) sound signal whose samples all have the same value.
180 BaseAudioContext.createConvolver() API, AudioContext, BaseAudioContext, Method, Reference, Web Audio API, createConvolver
A ConvolverNode.
181 BaseAudioContext.createDelay() API, AudioContext, BaseAudioContext, Method, Reference, Web Audio API, createDelay
The createDelay() method of the BaseAudioContext Interface is used to create a DelayNode, which is used to delay the incoming audio signal by a certain amount of time.
182 BaseAudioContext.createDynamicsCompressor() API, AudioContext, BaseAudioContext, Method, Reference, Web Audio API, createDynamicsCompressor
Compression lowers the volume of the loudest parts of the signal and raises the volume of the softest parts. Overall, a louder, richer, and fuller sound can be achieved. It is especially important in games and musical applications where large numbers of individual sounds are played simultaneously, where you want to control the overall signal level and help avoid clipping (distorting) of the audio output.
183 BaseAudioContext.createGain() API, Audio, AudioContext, BaseAudioContext, Method, Reference, Volume Control, Web Audio API, createGain, sound
A GainNode which takes as input one or more audio sources and outputs audio whose volume has been adjusted in gain (volume) to a level specified by the node's GainNode.gain a-rate parameter.
184 BaseAudioContext.createIIRFilter() API, Audio, AudioContext, BaseAudioContext, CreateIIRFilter, Method, Reference, Web Audio API, filter
The createIIRFilter() method of the BaseAudioContext interface creates an IIRFilterNode, which represents a general infinite impulse response (IIR) filter which can be configured to serve as various types of filter.
185 BaseAudioContext.createOscillator() API, AudioContext, BaseAudioContext, Method, Reference, Web Audio API, createOscillator
The createOscillator() method of the BaseAudioContext interface creates an OscillatorNode, a source representing a periodic waveform. It basically generates a constant tone.
186 BaseAudioContext.createPanner() API, AudioContext, BaseAudioContext, Method, Reference, Web Audio API, createPanner
The panner node is spatialized in relation to the AudioContext's AudioListener (defined by the AudioContext.listener attribute), which represents the position and orientation of the person listening to the audio.
187 BaseAudioContext.createPeriodicWave() API, Audio, AudioContext, BaseAudioContext, Media, Method, Reference, Web Audio API, createPeriodicWave
The createPeriodicWave() method of the BaseAudioContext Interface is used to create a PeriodicWave, which is used to define a periodic waveform that can be used to shape the output of an OscillatorNode.
188 BaseAudioContext.createScriptProcessor() API, AudioContext, BaseAudioContext, Method, Reference, Web Audio API, createScriptProcessor
A ScriptProcessorNode.
189 BaseAudioContext.createStereoPanner() API, AudioContext, BaseAudioContext, Media, Method, Reference, Web Audio API, createStereoPanner
A StereoPannerNode.
190 BaseAudioContext.createWaveShaper() API, AudioContext, BaseAudioContext, Method, Reference, Web Audio API, createWaveShaper
A WaveShaperNode.
191 BaseAudioContext.currentTime API, AudioContext, BaseAudioContext, Property, Reference, Web Audio API, currentTime
The currentTime read-only property of the BaseAudioContext interface returns a double representing an ever-increasing hardware timestamp in seconds that can be used for scheduling audio playback, visualizing timelines, etc. It starts at 0.
192 BaseAudioContext.decodeAudioData() API, Audio, AudioContext, BaseAudioContext, Method, Reference, Web Audio API, decodeAudioData
This is the preferred method of creating an audio source for Web Audio API from an audio track. This method only works on complete file data, not fragments of audio file data.
193 BaseAudioContext.destination API, AudioContext, BaseAudioContext, Property, Reference, Web Audio API, destination
An AudioDestinationNode.
194 BaseAudioContext.listener API, AudioContext, BaseAudioContext, Property, Reference, Web Audio API, listener, spatialization
An AudioListener object.
195 BaseAudioContext.onstatechange API, Audio, AudioContext, BaseAudioContext, Event Handler, Reference, Web Audio API, onstatechange
The following snippet is taken from our AudioContext states demo (see it running live.) The onstatechange hander is used to log the current state to the console every time it changes.
196 BaseAudioContext.resume() API, Audio, AudioContext, BaseAudioContext, Method, Reference, Web Audio API, resume
The resume() method of the BaseAudioContext Interface resumes the progression of time in an audio context that has previously been suspended.
197 BaseAudioContext.sampleRate API, AudioContext, BaseAudioContext, Property, Reference, Web Audio API, sampleRate
A floating point number.
198 BaseAudioContext.state API, Audio, AudioContext, BaseAudioContext, Property, Reference, Web Audio API, state
A DOMString. Possible values are:
199 BasicCardRequest API, Basic Card Payment, BasicCardRequest, Experimental, Interface, Payment Request, Payment Request API, Reference
The BasicCardRequest dictionary is a JavaScript object-structure that can be used in the Payment Request API. The properties of BasicCardRequest are defined in the Basic Card Payment spec).
200 BasicCardRequest.supportedNetworks API, Basic Card Payment, BasicCardRequest, Experimental, Payment Request, Payment Request API, Property, Reference, supportedNetworks
The supportedNetworks property of the BasicCardRequest dictionary contains an array of DOMStrings representing the card networks that the retailer supports (e.g. amex, mastercard).
201 BasicCardRequest.supportedTypes API, Basic Card Payment, BasicCardRequest, Experimental, Payment Request, Payment Request API, Property, Reference, supportedTypes
The supportedTypes property of the BasicCardRequest dictionary contains an array of DOMStrings representing the card types that the retailer supports (e.g. credit, debit, prepaid).
202 BasicCardResponse API, Basic Card Payment, BasicCardResponse, Experimental, Interface, Payment Request, Payment Request API, Reference
The BasicCardResponse dictionary (related to the Payment Request API, although defined in the Basic Card Payment spec) defines an object structure for payment response details such as the number/expiry date of the card used to make the payment, and the billing address.
203 BasicCardResponse.billingAddress API, Basic Card Payment, BasicCardResponse, Experimental, Payment Request, Payment Request API, Property, Reference, billingAddress
The billingAddress property of the BasicCardResponse dictionary contains the billing address of the card used to make the payment.
204 BasicCardResponse.cardNumber API, Basic Card Request, BasicCardResponse, Experimental, Payment Request, Payment Request API, Property, Reference, cardNumber
The cardNumber property of the BasicCardResponse dictionary contains the number of the card used to make the payment.
205 BasicCardResponse.cardSecurityCode API, Basic Card Payment, BasicCardResponse, Experimental, Payment Request, Payment Request API, Property, Reference, cardSecurityCode
The cardSecurityCode property of the BasicCardResponse dictionary contains the security code of the card used to make the payment.
206 BasicCardResponse.cardholderName API, Basic Card Payment, BasicCardResponse, Experimental, Payment Request, Payment Request API, Property, Reference, cardholderName
The cardNumber property of the BasicCardResponse dictionary contains the cardholder name of the card used to make the payment.
207 BasicCardResponse.expiryMonth API, Basic Card Payment, BasicCardResponse, Experimental, Payment Request, Payment Request API, Property, Reference, expiryMonth
The expiryMonth property of the BasicCardResponse dictionary contains the expiry month of the card used to make the payment.
208 BasicCardResponse.expiryYear API, Basic Card Payment, BasicCardResponse, Experimental, Payment Request, Payment Request API, Property, Reference, expiryYear
The expiryYear property of the BasicCardResponse dictionary contains the expiry year of the card used to make the payment.
209 Battery Status API API, Apps, Battery, Battery API, Battery Status API, Firefox OS, Guide, Mobile, Overview
The Battery Status API, more often referred to as the Battery API, provides information about the system's battery charge level and lets you be notified by events that are sent when the battery level or charging status change. This can be used to adjust your app's resource usage to reduce battery drain when the battery is low, or to save changes before the battery runs out in order to prevent data loss.
210 BatteryManager API, Battery API, Device API, Interface, Obsolete, Reference, Référence(2)
The BatteryManager interface provides ways to get information about the system's battery charge level.
211 BatteryManager.charging API, Battery API, NeedsMarkupWork, Property, Reference, Référence(2)
A Boolean value indicating whether or not the device's battery is currently being charged.
212 BatteryManager.chargingTime API, Battery API, NeedsMarkupWork, Property, Reference, Référence(2)
Indicates the amount of time, in seconds, that remain until the battery is fully charged.
213 BatteryManager.dischargingTime API, Battery API, NeedsMarkupWork, Property, Reference, Référence(2)
Indicates the amount of time, in seconds, that remains until the battery is fully discharged.
214 BatteryManager.level API, Battery API, NeedsMarkupWork, Property, Reference, Référence(2)
Indicates the current battery charge level as a value between 0.0 and 1.0.
215 BatteryManager.onchargingchange API, Battery API, Event Handler, NeedsMarkupWork, Property, Reference, Référence(2)
Specifies an event listener to receive chargingchange events. These events occur when the battery charging state is updated.
216 BatteryManager.onchargingtimechange API, Battery API, Event Handler, NeedsMarkupWork, Property, Reference, Référence(2)
Specifies an event listener to receive chargingtimechange events. These events occur when the battery chargingTime is updated.
217 BatteryManager.ondischargingtimechange API, Battery API, Event Handler, NeedsMarkupWork, Property, Reference, Référence(2)
Specifies an event listener to receive dischargingtimechange events. These events occur when the battery dischargingTime is updated.
218 BatteryManager.onlevelchange API, Battery API, Event Handler, NeedsMarkupWork, Property, Reference, Référence(2)
Specifies an event listener to receive levelchange events. These events occur when the battery level is updated.
219 Beacon API Guide, Overview, Web Performance
The Beacon interface is used to schedule an asynchronous and non-blocking request to a web server. Beacon requests use the HTTP POST method and requests typically do not require a response. Requests are guaranteed to be initiated before a page is unloaded and they are run to completion, without requiring a blocking request (for example XMLHttpRequest).
220 Using the Beacon API Guide, Web Performance
The Beacon interface schedules an asynchronous and non-blocking request to a web server. Beacon requests use HTTP POST and requests do not require a response. Requests are guaranteed to be initiated before a page is unloaded and they are run to completion without requiring a blocking request (for example XMLHttpRequest).
221 BeforeInstallPromptEvent API, BeforeInstallPromptEvent, Event, Experimental, Interface, Reference
The BeforeInstallPromptEvent is fired at the Window.onbeforeinstallprompt handler before a user is prompted to "install" a web site to a home screen on mobile.
222 BeforeInstallPromptEvent.prompt() API, BeforeInstallPromptEvent, Experimental, Method, Reference, prompt
The prompt() method of the BeforeInstallPromptEvent interface allows a developer to show the install prompt at a time of their own choosing. 
223 BeforeUnloadEvent API, Reference
The beforeunload event is fired when the window, the document and its resources are about to be unloaded.
224 BiquadFilterNode API, BiquadFilterNode, Interface, NeedsMobileBrowserCompatibility, Reference, Web Audio API
The BiquadFilterNode interface represents a simple low-order filter, and is created using the AudioContext.createBiquadFilter() method. It is an AudioNode that can represent different kinds of filters, tone control devices, and graphic equalizers.
225 BiquadFilterNode() API, Audio, BiquadFilterNode, Constructor, Media, Reference, Web Audio API
The BiquadFilterNode() constructor of the Web Audio API creates a new BiquadFilterNode object, which represents a simple low-order filter, and is created using the AudioContext.createBiquadFilter() method.
226 BiquadFilterNode.Q API, BiquadFilterNode, Property, Q, Reference, Web Audio API
An AudioParam.
227 BiquadFilterNode.detune API, BiquadFilterNode, Property, Reference, Référence(2), Web Audio API, detune
An a-rate AudioParam.
228 BiquadFilterNode.frequency API, BiquadFilterNode, Property, Reference, Web Audio API, frequency
An AudioParam.
229 BiquadFilterNode.gain API, BiquadFilterNode, Gain, Property, Reference, Référence(2), Web Audio API
An AudioParam.
230 BiquadFilterNode.getFrequencyResponse() API, Audio, BiquadFilterNode, Method, Reference, Web Audio API, filter, getFrequencyResponse
undefined
231 BiquadFilterNode.type API, BiquadFilterNode, Property, Reference, Référence(2), Type, Web Audio API
A string (enum) representing a BiquadFilterType.
232 Blob API, Files, NeedsMobileBrowserCompatibility, Reference, WebAPI
A Blob object represents a file-like object of immutable, raw data. Blobs represent data that isn't necessarily in a JavaScript-native format. The File interface is based on Blob, inheriting blob functionality and expanding it to support files on the user's system.
233 Blob() API, Blob, Constructor, Experimental, Expérimental(2), File API, Reference, Référence(2)
The Blob() constructor returns a new Blob object. The content of the blob consists of the concatenation of the values given in the parameter array.
234 Blob.size API, Files, Property, Reference, Référence(2), Web API
The Blob.size property returns the size in bytes of the Blob or a File.
235 Blob.slice() API, Files, Method, Reference
The Blob.slice() method is used to create a new Blob object containing the data in the specified range of bytes of the source Blob.
236 Blob.type API, DOM, File, Files, Property, Reference
The type property of a Blob object provides the MIME type of the file. It returns an empty string if the type couldn't determined.
237 BlobBuilder API, DOM, DOM Reference, File API, Obsolete, Reference, Référence(2)
The BlobBuilder interface provides an easy way to construct Blob objects. Just create a BlobBuilder and append chunks of data to it by calling the append() method. When you're done building your blob, call getBlob() to retrieve a Blob containing the data you sent into the blob builder.
238 BlobEvent API, Audio, Blob, Interface, Media, MediaStream Recording, MediaStream Recording API, Recording Media, Reference, Video, events
The BlobEvent interface represents events associated with a Blob. These blobs are typically, but not necessarily,  associated with media content.
239 BlobEvent.BlobEvent() API, BlobEvent, Constructor, DOM, DOM Reference, Experimental, Media Stream Encoding, Reference
The BlobEvent() constructor returns a newly created BlobEvent object with an associated Blob.
240 BlobEvent.data API, BlobEvent, DOM, DOM Reference, Experimental, Expérimental(2), Media Stream Recording, Property, Reference, Référence(2)
The BlobEvent.data read-only property represents a Blob associated with the event.
241 BlobEvent.timecode API, BlobEvent, Media, Media Stream Recording, Property, Reference
The timecode readonlyinline property of the BlobEvent interface a DOMHighResTimeStamp indicating the difference between the timestamp of the first chunk in data, and the timestamp of the first chunk in the first BlobEvent produced by this recorder.
242 Bluetooth API, Bluetooth, Interface, Non-standard, Reference, Web Bluetooth API
The Bluetooth interface of the Web Bluetooth API returns a Promise to a BluetoothDevice object with the specified options.
243 Bluetooth.requestDevice() API, Bluetooth, Method, Reference, Web Bluetooth API, requestDevice
The Bluetooth.requestDevice() method of the Bluetooth interface returns a Promise to a BluetoothDevice object with the specified options. If there is no chooser UI, this method returns the first device matching the criteria.
244 BluetoothAdvertisingData API, Bluetooth, BluetoothAdvertisingData, Interface, Non-standard, Reference, Web Bluetooth API
The BluetoothDevice interface of the Web Bluetooth API provides advertising data about a particular Bluetooth device.
245 BluetoothAdvertisingData.appearance API, Bluetooth, BluetoothAdvertisingData, Property, Reference, appearance
The appearance read-only property of the BluetoothAdvertisingData interface returns one of the values defined by the org.bluetooth.characteristic.gap.appearance characteristic.
246 manufacturerData API, Bluetooth, BluetoothAdvertisingData, Property, Reference, manufacturerData
The manufacturerData read-only property of the BluetoothAdvertisingData interface returns a map that relates Company Identifier Codes to ArrayBuffers.
247 rssi API, Bluetooth, BluetoothAdvertisingData, Property, Reference, rssi
The rssi read-only property of the BluetoothAdvertisingData interface returns the power at which the device’s packets are being received, measured in dBm. This is used to compute the path loss as this.txPower - this.rssi.
248 serviceData API, Bluetooth, BluetoothAdvertisingData, Property, Reference, serviceData
The serviceData read-only property of the BluetoothAdvertisingData interface returns a map that relates UUIDs to ArrayBuffers.
249 txPower API, Bluetooth, BluetoothAdvertisingData, Property, Reference, txPower
The txPower read-only property of the BluetoothAdvertisingData interface returns the transmission power at which the device is broadcasting, measured in dBm. This is used to compute the path loss as this.txPower - this.rssi.
250 BluetoothCharacteristicProperties API, Bluetooth, BluetoothCharacteristicProperties, BluetoothRemoveGATTCharacteristic, Interface, Non-standard, Reference, Web Bluetooth API
The BluetoothCharacteristicProperties interface of the the Web Bluetooth API provides an object provides propertieds of a particular BluetoothRemoteGATTCharacteristic.
251 BluetoothRemoteGATTCharacteristic API, Bluetooth, BluetoothGattCharacteristic, Interface, Non-standard, Reference, Web Bluetooth API
The BluetoothRemoteGattCharacteristic interface of the Web Bluetooth API represents a GATT Characteristic, which is a basic data element that provides further information about a peripheral’s service.
252 BluetoothRemoteGATTCharacteristic.getDescriptor() API, Bluetooth, BluetoothRemoteGATTCharacteristic, Non-standard, Property, Reference, Web Bluetooth API, getDescriptor()
The BluetoothRemoteGATTCharacteristic.getDescriptor() method returns a Promise that resolves to the first BluetoothGATTDescriptor for a given descriptor UUID.
253 BluetoothRemoteGATTCharacteristic.getDescriptors() API, Bluetooth, BluetoothRemoteGATTCharacteristic, Non-standard, Property, Reference, Web Bluetooth API, getDescriptors()
The BluetoothRemoteGATTCharacteristic.getDescriptors() method returns a Promise that resolves to an Array of all BluetoothGATTDescriptor objects for a given descriptor UUID.
254 BluetoothRemoteGATTCharacteristic.properties API, Bluetooth, BluetoothRemoteGATTCharacteristic, Non-standard, Property, Reference, Web Bluetooth API, properties
The BluetoothRemoteGATTCharacteristic.properties read-only property returns a BluetoothCharacteristicProperties instance containing the properties of this characteristic.
255 BluetoothRemoteGATTCharacteristic.readValue() API, Bluetooth, BluetoothRemoteGATTCharacteristic, Non-standard, Property, Reference, Web Bluetooth API, readValue
The BluetoothRemoteGATTCharacteristic.readValue() method returns a Promise that resolves to a DataView holding a duplicate of the value property if it is available and supported. Otherwise it throws an error.
256 BluetoothRemoteGATTCharacteristic.service API, Bluetooth, BluetoothRemoteGATTCharacteristic, Non-standard, Property, Reference, Service, Web Bluetooth API
The BluetoothRemoteGATTCharacteristic.service read-only property returns the BluetoothGATTService this characteristic belongs to.
257 BluetoothRemoteGATTCharacteristic.startNotifications() API, Bluetooth, BluetoothRemoteGATTCharacteristic, Non-standard, Property, Reference, Web Bluetooth API, startNotifications()
The BluetoothRemoteGATTCharacteristic.startNotifications() method returns a Promise to the BluetoothRemoteGATTCharacteristic instance when there is an active notification on it.
258 BluetoothRemoteGATTCharacteristic.stopNotifications() API, Bluetooth, BluetoothRemoteGATTCharacteristic, Non-standard, Property, Reference, Web Bluetooth API, stopNotifications
The BluetoothRemoteGATTCharacteristic.stopNotifications() method returns a Promise to the BluetoothRemoteGATTCharacteristic instance when there is no longer an active notification on it.
259 BluetoothRemoteGATTCharacteristic.uuid API, Bluetooth, BluetoothRemoteGATTCharacteristic, Non-standard, Property, Reference, Service, Web Bluetooth API, uuid
The BluetoothRemoteGATTCharacteristic.uuid read-only property returns DOMString containing the UUID of the characteristic, for example '00002a37-0000-1000-8000-00805f9b34fb' for the Heart Rate Measurement characteristic.
260 BluetoothRemoteGATTCharacteristic.value API, Bluetooth, BluetoothRemoteGATTCharacteristic, Non-standard, Property, Reference, Web Bluetooth API, value
The BluetoothRemoteGATTCharacteristic.value read-only property returns currently cached characteristic value. This value gets updated when the value of the characteristic is read or updated via a notification or indication.
261 BluetoothRemoteGATTCharacteristic.writeValue() API, Bluetooth, BluetoothRemoteGATTCharacteristic, Non-standard, Property, Reference, Web Bluetooth API, writeValue
The BluetoothRemoteGATTCharacteristic.writeValue() method sets the value property to the bytes contained in an ArrayBuffer and returns a Promise.
262 BluetoothRemoteGATTDescriptor API, Bluetooth, BluetoothGattDescriptor, BluetoothRemoteGATTDescriptor, Interface, Non-standard, Reference, Web Bluetooth API
The BluetoothRemoteGATTDescriptor  interface of the Web Bluetooth API provides a GATT Descriptor, which provides further information about a characteristic’s value.
263 characteristic API, Bluetooth, BluetoothGattDescriptor, BluetoothRemoteGATTDescriptor, Interface, Non-standard, Reference, Web Bluetooth API, characteristic
The BluetoothRemoteGATTDescriptor.characteristic read-only property returns the BluetoothRemoteGATTCharacteristic this descriptor belongs to.
264 readValue() API, Bluetooth, BluetoothGattDescriptor, BluetoothRemoteGATTDescriptor, Interface, Non-standard, Reference, Web Bluetooth API, readValue()
The BluetoothRemoteGATTDescriptor.readValue() method returns a Promise that resolves to an ArrayBuffer holding a duplicate  of the value property if it is available and supported. Otherwise it throws an error.
265 uuid API, Bluetooth, BluetoothRemoteGATTDescriptor, Interface, Non-standard, Reference, Web Bluetooth API, uuid
The BluetoothRemoteGATTDescriptor.uuid read-only property returns the UUID of the characteristic descriptor, for example '00002902-0000-1000-8000-00805f9b34fb' for theClient Characteristic Configuration descriptor.
266 value API, Bluetooth, BluetoothGattDescriptor, BluetoothRemoteGATTDescriptor, Interface, Non-standard, Reference, Web Bluetooth API, value
The BluetoothRemoteGATTDescriptor.value read-only property returns an ArrayBuffer containing the currently cached descriptor value. This value gets updated when the value of the descriptor is read.
267 writeValue() API, Bluetooth, BluetoothGattDescriptor, BluetoothRemoteGATTDescriptor, Interface, Non-standard, Reference, Web Bluetooth API, writeValue()
The BluetoothRemoteGATTDescriptor.writeValue() method sets the value property to the bytes contained in an ArrayBuffer and returns a Promise.
268 BluetoothRemoteGATTServer API, Bluetooth, BluetoothGATTRemoteServer, Interface, Non-standard, Reference, Web Bluetooth API
The BluetoothRemoteGATTServer interface of the Web Bluetooth API represents a GATT Server on a remote device.
269 BluetoothRemoteGATTServer.connect() API, Bluetooth, BluetoothRemoteGATTServer, Method, Non-standard, Reference, Web Bluetooth API, connect()
The BluetoothRemoteGATTServer.connect() method causes the script execution environment to connect to this.device.
270 BluetoothRemoteGATTServer.connected API, Bluetooth, BluetoothRemoteGATTServer, Non-standard, Property, Reference, Web Bluetooth API
The BluetoothRemoteGATTServer.connected read-only property returns a boolean value that returns true while this script execution environment is connected to this.device. It can be false while the user agent is physically connected.
271 BluetoothRemoteGATTServer.device
The BluetoothRemoteGATTServer.device read-only property returns a reference to the BluetoothDevice running the server.
272 BluetoothRemoteGATTServer.disconnect() API, Bluetooth, BluetoothRemoteGATTServer, Method, Non-standard, Reference, Web Bluetooth API, disconnect()
The BluetoothRemoteGATTServer.disconnect() method causes the script execution environment to disconnect from this.device.
273 BluetoothRemoteGATTServer.getPrimaryService() API, Bluetooth, BluetoothRemoteGATTServer, Method, Non-standard, Reference, Web Bluetooth API, getPrimaryService()
The BluetoothRemoteGATTServer.getPrimaryService() method returns a promise to the primary BluetoothGATTService offered by the bluetooth device for a specified BluetoothServiceUUID.
274 BluetoothRemoteGATTServer.getPrimaryServices() API, Bluetooth, BluetoothRemoteGATTServer, Method, Non-standard, Reference, Web Bluetooth API, getPrimaryServices()
The BluetoothRemoteGATTServer.getPrimaryServices() method returns a promise to a list of primary BluetoothGATTService objects offered by the bluetooth device for a specified BluetoothServiceUUID.
275 BluetoothRemoteGATTService API, Bluetooth, BluetoothGattService, BluetoothRemoteGATTService, Interface, Non-standard, Reference, Web Bluetooth API
The BluetoothRemoteGATTService interface of the Web Bluetooth API represents a service provided by a GATT server, including a device, a list of referenced services, and a list of the characteristics of this service.
276 device API, Bluetooth, BluetoothGattService, Device, Non-standard, Property, Reference, Web Bluetooth API
The BluetoothGATTService.device read-only property returns information about a Bluetooth device through an instance of BluetoothDevice.
277 getCharacteristic() API, Bluetooth, BluetoothGattService, Non-standard, Property, Reference, Web Bluetooth API, getCharacteristic()
The BluetoothGATTService.getCharacteristic() method returns a Promise to an instance of BluetoothGATTCharacteristic for a given universally unique identifier (UUID).
278 getCharacteristics() API, Bluetooth, BluetoothGattService, Non-standard, Property, Reference, Web Bluetooth API, getCharacteristics()
The BluetoothGATTService.getCharacteristics() method returns a Promise to a list of BluetoothGATTCharacteristic instances for a given universally unique identifier (UUID).
279 getIncludedService() API, Bluetooth, BluetoothGattService, Non-standard, Property, Reference, Web Bluetooth API, getIncludedService
The BluetoothGATTService.getIncludedService() method returns a Promise to an instance of BluetoothGATTService for a given universally unique identifier (UUID).
280 getIncludedServices() API, Bluetooth, BluetoothGattService, Non-standard, Property, Reference, Web Bluetooth API, getIncludedServices()
The BluetoothGATTService.getIncludedServices() method returns a Promise to an Array of BluetoothGATTService instances for an optional universally unique identifier (UUID).
281 isPrimary API, Bluetooth, BluetoothGattService, Non-standard, Property, Reference, Web Bluetooth API, isPrimary
The BluetoothGATTService.isPrimary read-only property returns a Boolean that indicates whether this is a primary service. If it is not a primary service, it is a secondary service.
282 uuid API, Bluetooth, BluetoothGattService, Non-standard, Property, Reference, Web Bluetooth API, uuid
The BluetoothGATTService.uuid read-only property returns a DOMString representing the UUID of this service.
283 BluetoothStatusChangedEvent API, Firefox OS, Reference, Référence(2), Web Bluetooth
The BluetoothStatusChangedEvent API provides access to information regarding any change to the status of a Bluetooth device.
284 BluetoothStatusChangedEvent.address API, Firefox OS, Property, Reference, Référence(2), Web Bluetooth
The address property represents the address of the device for which the status has changed in the Bluetooth micro-network.
285 BluetoothStatusChangedEvent.status API, Firefox OS, Property, Reference, Référence(2), Web Bluetooth
The status property indicates if the connection is active (true) or not (false).
286 Body API, BODY, Experimental, Fetch, Fetch API, Interface, Reference, request
The Body mixin of the Fetch API represents the body of the response/request, allowing you to declare what its content type is and how it should be handled.
287 Body.arrayBuffer() API, ArrayBuffer, BODY, Experimental, Expérimental(2), Fetch, Method, Reference, Référence(2)
The arrayBuffer() method of the Body mixin takes a Response stream and reads it to completion. It returns a promise that resolves with an ArrayBuffer.
288 Body.blob() API, BODY, Blob, Experimental, Fetch, Method, Reference
The blob() method of the Body mixin takes a Response stream and reads it to completion. It returns a promise that resolves with a Blob.
289 Body.body API, BODY, Experimental, Fetch, Property, Reference, Streams
The body read-only property of the Body mixin is a simple getter used to expose a ReadableStream of the body contents.
290 Body.bodyUsed API, BODY, Experimental, Fetch, Property, Reference, bodyUsed
The bodyUsed read-only property of the Body mixin contains a Boolean that indicates whether the body has been read yet.
291 Body.formData() API, BODY, Experimental, Fetch, Fetch API, FormData, Method, NeedsExample, Reference
The formData() method of the Body mixin takes a Response stream and reads it to completion. It returns a promise that resolves with a FormData object.
292 Body.json() API, BODY, Experimental, Fetch, JSON, Method, Reference
The json() method of the Body mixin takes a Response stream and reads it to completion. It returns a promise that resolves with the result of parsing the body text as JSON.
293 Body.text() API, BODY, Experimental, Fetch, Method, Reference, Text
The text() method of the Body mixin takes a Response stream and reads it to completion. It returns a promise that resolves with a USVString object (text). The response is always decoded using UTF-8.
294 Broadcast Channel API API, Broadcast Channel API, HTML API, Overview, Reference
The Broadcast Channel API allows simple communication between browsing contexts (that is windows, tabs, frames, or iframes) with the same origin (usually pages from the same site).
295 BroadcastChannel API, Broadcast Channel API, Experimental, HTML API, Interface, Reference
The BroadcastChannel interface represents a named channel that any browsing context of a given origin can subscribe to. It allows communication between different documents (in different windows, tabs, frames or iframes) of the same origin. Messages are broadcasted via a message event fired at all BroadcastChannel objects listening to the channel.
296 BroadcastChannel() API, Broadcast Channel API, BroadcastChannel, Constructor, Experimental, HTML API, Reference
The BroadcastChannel() constructor creates a new BroadcastChannel and connects it to the underlying channel.
297 BroadcastChannel.close() API, Broadcast Channel API, BroadcastChannel, Experimental, HTML API, Method, Reference
The BroadcastChannel.close() terminates the connection to the underlying channel, allowing the object to be garbage collected. This is a necessary step to perform as there is no other way for a browser to know that this channel is not needed anymore.
298 BroadcastChannel.name Broadcast Channel API, BroadcastChannel, Experimental, HTML API, Property, Read-only, Reference
The read-only BroadcastChannel.name property returns a DOMString, which uniquely identifies the given channel with its name. This name is passed to the BroadcastChannel() constructor at creation time and is therefore read-only.
299 BroadcastChannel.onmessage API, Broadcast Channel API, BroadcastChannel, Event Handler, Experimental, HTML API, Property, Reference
The BroadcastChannel.onmessage event handler is a property that specifies the function to execute when a message event, of type MessageEvent, is received by this BroadcastChannel. Such an event is sent by the browser with a message broadcasted to the channel.
300 BroadcastChannel.onmessageerror API, BroadcastChannel, Event Handler, Property, Reference, onmessageerror
The onmessageerror event handler of the BroadcastChannel interface is an EventListener, called whenever an MessageEvent of type messageerror is fired on the BroadcastChannel instance — that is, when it receives a message that cannot be deserialized.
301 BroadcastChannel.postMessage() API, Broadcast Channel API, BroadcastChannel, Experimental, HTML API, Method, Reference
The BroadcastChannel.postMessage() sends a message, which can be of any kind of Object, to each listener in any browser context with the same origin. The message is transmitted as a message event targeted at each BroadcastChannel bound to the channel.
302 BudgetService API, BudgetService, Interface, Reference, Web Budget API
The BudgetService interface of the Web Budget API provides a programmatic interface to the user agent’s budget service. It is available in both document and worker environments.
303 BudgetService.getBudget() API, BudgetService, Method, Reference, Web Budget API, getBudget
The getBudget() property of the BudgetService interface returns a Promise that resolves to an array of BudgetState objects indicating the expected state of the budget at times in the future.
304 BudgetService.getCost() API, BudgetService, Method, Reference, Web Budget API, getCost
The getCost() property of the BudgetService interface returns a Promise that resolves to a double indicating the worst-case background operation cost of the provided background operation.
305 BudgetService.reserve() API, BudgetService, Method, Reference, Web Budget API, reserve
The reserve() property of the BudgetService interface returns a Promise that resolves to a boolean indicating whether the requested budget operation can be reserved.
306 BudgetState API, BudgetState, Interface, Reference, Web Budget API
The BudgetState interface of the the Web Budget API provides the amount of the user agent's processing budget at a specific point in time.
307 BudgetState.budgetAt API, BudtetState, Property, Reference, Web Budget API, budgetAt
The budgetAt read-only property of the BudgetState interface returns the anticipated processing budget at the specified time.
308 BudgetState.time API, BudgetState, Property, Reference, Time, Web Budget API
The time read-only property of the BudgetState interface returns a timestamp at which the budgetAt value is valid.
309 BufferSource API, Interface, JavaScript, Reference, Référence(2), Typed Arrays
BufferSource is a typedef used to represent objects that are either themselves an ArrayBuffer, or which are a TypedArray providing an ArrayBufferView.
310 ByteLengthQueuingStrategy API, ByteLengthqueueingStrategy, Experimental, Interface, Reference, Streams
The ByteLengthQueuingStrategy interface of the the Streams API provides a built-in byte length queuing strategy that can be used when constructing streams.
311 ByteLengthQueuingStrategy.ByteLengthQueuingStrategy() API, ByteLengthQueuingStrategy, Constructor, Experimental, Reference, Streams
The ByteLengthQueuingStrategy() constructor creates and returns a ByteLengthQueuingStrategy() object instance.
312 ByteLengthQueuingStrategy.size() API, ByteLengthqueueingStrategy, Experimental, Method, Reference, Streams, size
The size() method of the ByteLengthQueueingStrategy interface returns the given chunk’s byteLength property.
313 ByteString API, DOM, DOM Reference, Reference, Référence(2), String, WebIDL
ByteString is a UTF-8 String that corresponds to the set of all possible sequences of bytes. ByteString maps to a String when returned in JavaScript; generally, it's only used when interfacing with protocols that use bytes and strings interchangably, such as HTTP.
314 CDATASection API, DOM, Deprecated, Reference
The CDATASection interface represents a CDATA section that can be used within XML to include extended portions of unescaped text, such that the symbols < and & do not need escaping as they normally do within XML when used as text.
315 CSS API, CSSOM, Interface, Painting, Reference
The CSS interface holds useful CSS-related methods. No object with this interface are implemented: it contains only static methods and therefore is a utilitarian interface.
316 CSS.escape() API, CSS, CSSOM, Method, Reference, Static, escape()
The CSS.escape() static method returns a DOMString containing the escaped string passed as parameter, mostly for use as part of a CSS selector.
317 CSS.supports() API, CSSOM, Method, Reference
The CSS.supports() static methods returns a Boolean value indicating if the browser supports a given CSS feature, or not.
318 CSS Counter Styles CSS, CSS Counter Styles, Overview
The CSS Counter Styles module allows to define custom counter styles, which can be used for CSS list-marker and generated-content counters.
319 CSS Font Loading API API, CSSFontLoading, Experimental, Fonts, NeedsContent, Reference
The CSS Font Loading API provides events and interfaces for dynamically loading font resources.
320 CSS Object Model API, CSSOM, Reference
The CSS Object Model is a set of APIs allowing the manipulation of CSS from JavaScript. It is much like the DOM, but for the CSS rather than the HTML. It allows users to read and modify CSS style dynamically.
321 Determining the dimensions of elements CSSOM View, Client width, Guide, Intermediate, NeedsCompatTable, NeedsSpecTable, client height, offsetHeight, offsetWidth, size of displayed content
There are several properties you can look at in order to determine the width and height of elements, and it can be tricky to determine which is the right one for your needs. This article is designed to help you make that decision.  Note that all these properties are read-only.  If you want to set the width and height of an element, use width and height or the overriding min-width and max-width, and min-height and max-height properties.
322 Managing screen orientation Advanced, CSSOM View, Guide, Screen Orientation
Screen orientation is something slightly different than device orientation. Even if a device doesn't have the capacity to detect its own orientation, a screen always has one. And if a device is able to know its orientation, it's good to have the ability to control the screen orientation in order to preserve or adapt the interface of a web application.
323 Using dynamic styling information Beginner, CSSOM, NeedsBeginnerUpdate
The CSS Object Model (CSSOM), part of the DOM, exposes specific interfaces allowing manipulation of a wide amount of information regarding CSS. Initially defined in the DOM Level 2 Style recommendation, these interfaces forms now a specification, CSS Object Model (CSSOM) which aims at superseding it.
324 CSSConditionRule API, CSSOM, Interface, Reference
An object implementing the CSSConditionRule interface represents a single condition CSS at-rule, which consists of a condition and a statement block. It is a child of CSSGroupingRule.
325 CSSCounterStyleRule API, CSS Counter Styles, Interface, Reference
The CSSCounterStyleRule interface represents an @counter-style at-rule.
326 CSSGroupingRule API, CSSOM, Interface, Reference
An object implementing the CSSGroupingRule interface represents any CSS at-rule that contains other rules nested within it.
327 CSSKeyframeRule API, CSS Animations, CSSOM, Experimental, Interface, Reference
The CSSKeyframeRule interface describes an object representing a set of style for a given keyframe. It corresponds to the contains of a single keyframe of a @keyframes at-rule. It implements the CSSRule interface with a type value of 8 (CSSRule.KEYFRAME_RULE).
328 CSSKeyframesRule API, CSS Animations, CSSOM, Experimental, Interface, Reference
The CSSKeyframesRule interface describes an object representing a complete set of keyframes for a CSS animation. It corresponds to the contains of a whole @keyframes at-rule. It implements the CSSRule interface with a type value of 7 (CSSRule.KEYFRAMES_RULE).
329 CSSMatrix API, NeedsBrowserCompatibility, Reference
A CSSMatrix represents a homogeneous 4x4 matrix to which 2D or 3D transforms can be applied. This class was allegedly part of CSS Transitions Module Level 3 at some point, but is not present in the current Working Draft. Use DOMMatrix instead.
330 CSSMediaRule API, CSSOM, Interface, Reference
The CSSMediaRule is an interface representing a single CSS @media rule. It implements the CSSConditionRule interface, and therefore the CSSGroupingRule and the CSSRule interface with a type value of 4 (CSSRule.MEDIA_RULE).
331 CSSNamespaceRule API, CSSOM, Interface, Reference
The CSSNamespaceRule interface describes an object representing a single CSS @namespace at-rule. It implements the CSSRule interface, with a type value of 10 (CSSRule.NAMESPACE_RULE).
332 CSSNamespaceRule.namespaceURI API, CSSNamespaceRule, CSSOM, Property, Reference, namespaceURI
The CSSNamespaceRule.namespaceURI read-only property returns a DOMString containing the text of the URI of the given namespace.
333 CSSNamespaceRule.prefix API, CSSNamespaceRule, CSSOM, Property, Reference, prefix
The CSSNamespaceRule.prefix read-only property returns a DOMString with the name of the prefix associated to this namespace. If there is no such prefix, returns  null.
334 CSSOMString API, CSSOM, Reference
CSSOMString is used to denote string data in CSSOM specifications and can refer to either DOMString or USVString. When a specification says CSSOMString, it depends on the browser vendors to choose whether to use DOMString or USVString. While browser implementations that use UTF-8 internally to represent strings in memory can use USVString when the specification says CSSOMString, implementations that already represent strings as 16-bit sequences might choose to use DOMString instead.
335 CSSPageRule API, CSSOM, Interface, Reference
CSSPageRule is an interface representing a single CSS @page rule. It implements the CSSRule interface with a type value of 6 (CSSRule.PAGE_RULE).
336 CSSPrimitiveValue API, CSSPrimitiveValue, Interface, NeedsBrowserCompatibility, NeedsMobileBrowserCompatibility, Reference
The CSSPrimitiveValue interface derives from the CSSValue interface and represents the current computed value of a CSS property.
337 CSSPrimitiveValue.getCounterValue() API, CSSPrimitiveValue, Method, NeedsBrowserCompatibility, NeedsExample, NeedsMobileBrowserCompatibility, getCounterValue
The getCounterValue() method of the CSSPrimitiveValue interface is used to get the counter value. If this CSS value doesn't contain a counter value, a DOMException is raised. Modification to the corresponding style property can be achieved using the Counter interface.
338 CSSPrimitiveValue.getFloatValue() API, CSSPrimitiveValue, Method, NeedsBrowserCompatibility, NeedsMobileBrowserCompatibility, getFloatValue
The getFloatValue() method of the CSSPrimitiveValue interface is used to get a float value in a specified unit. If this CSS value doesn't contain a float value or can't be converted into the specified unit, a DOMException is raised.
339 CSSPrimitiveValue.getRGBColorValue() API, CSSPrimitiveValue, Method, NeedsBrowserCompatibility, NeedsMobileBrowserCompatibility, getRGBColorValue
The getRGBColorValue() method of the CSSPrimitiveValue interface is used to get an RGB color value. If this CSS value doesn't contain a RGB color value, a DOMException is raised. Modification to the corresponding style property can be achieved using the RGBColor interface.
340 CSSPrimitiveValue.getRectValue() API, CSSPrimitiveValue, Method, NeedsBrowserCompatibility, NeedsMobileBrowserCompatibility, getRectValue
The getRectValue() method of the CSSPrimitiveValue interface is used to get a rect value. If this CSS value doesn't contain a rect value, a DOMException is raised. Modification to the corresponding style property can be achieved using the Rect interface.
341 CSSPrimitiveValue.getStringValue() API, CSSPrimitiveValue, Method, NeedsBrowserCompatibility, NeedsMobileBrowserCompatibility, getStringValue
The getStringValue() method of the CSSPrimitiveValue interface is used to get a string value. If this CSS value doesn't contain a string value, a DOMException is raised.
342 CSSPrimitiveValue.primitiveType API, CSSPrimitiveValue, NeedsBrowserCompatibility, NeedsMobileBrowserCompatibility, Property, Read-only, Reference, primitiveValue
The primitiveType read-only property of the CSSPrimitiveValue interface represents the type of a CSS value.
343 CSSPrimitiveValue.setFloatValue() API, CSSPrimitiveValue, Method, NeedsBrowserCompatibility, NeedsExample, NeedsMobileBrowserCompatibility, setFloatValue
The setFloatValue() method of the CSSPrimitiveValue interface is used to set a float value. If the property attached to this value can't accept the specified unit or the float value, the value will be unchanged and a DOMException will be raised.
344 CSSPrimitiveValue.setStringValue() API, CSSPrimitiveValue, Method, NeedsBrowserCompatibility, NeedsExample, NeedsMobileBrowserCompatibility, setStringValue
The setStringValue() method of the CSSPrimitiveValue interface is used to set a string value. If the property attached to this value can't accept the specified unit or the string value, the value will be unchanged and a DOMException will be raised.
345 CSSRule API, CSSOM, Interface, Reference
The CSSRule interface represents a single CSS rule. There are several types of rules, listed in the Type constants section below.
346 CSSRule.cssText API, CSSOM, NeedsCompatTable, NeedsSpecTable, NeedsWarkupWork, Property, Reference
cssText returns the actual text of a CSSStyleSheet style-rule.
347 CSSRule.parentStyleSheet API, CSSOM, NeedsCompatTable, NeedsMarkupWork, NeedsSpecTable, Property, Reference
parentStyleSheet returns the stylesheet object in which the current rule is defined.
348 CSSRuleList API, CSSOM, Interface, NeedsBrowserCompatibility, NeedsCompatTable, Reference
A CSSRuleList is an (indirect-modify only) array-like object containing an ordered collection of CSSRule objects.
349 CSSStyleDeclaration API, CSSOM, Interface, NeedsCompatTable, NeedsMarkupWork, Reference
CSSStyleDeclaration represents a collection of CSS property-value pairs. It is used in a few APIs:
350 CSSStyleDeclaration.cssText
cssText returns or sets the text of the element's inline style declaration only. To be able to set a stylesheet rule dynamically, see Using dynamic styling information.
351 CSSStyleDeclaration.getPropertyCSSValue() API, CSSOM, Method, Obsolete, Reference
The CSSStyleDeclaration.getPropertyCSSValue() method interface returns a CSSValue containing the CSS value for a property.
352 CSSStyleDeclaration.getPropertyPriority() API, CSSOM, Method, Reference
The CSSStyleDeclaration.getPropertyPriority() method interface returns a DOMString that provides all explicitly set priorities on the CSS property.
353 CSSStyleDeclaration.getPropertyValue() API, CSSOM, Method, Reference
The CSSStyleDeclaration.getPropertyValue() method interface returns a DOMString containing the value of a specified CSS property.
354 CSSStyleDeclaration.item() API, CSSOM, Method, Reference
The CSSStyleDeclaration.item() method interface returns a CSS property name from a CSSStyleDeclaration by index
355 CSSStyleDeclaration.length API, CSSOM, Property, Reference
The read-only property returns an integer that represents the number of style declarations in this CSS declaration block.
356 CSSStyleDeclaration.parentRule API, CSSOM, Property, Reference
The CSSStyleDeclaration.parentRule read-only property returns a CSSRule that is the parent of this style block
357 CSSStyleDeclaration.removeProperty() API, CSSOM, Method, Reference
The CSSStyleDeclaration.removeProperty() method interface removes a property from a CSS style declaration object.
358 CSSStyleDeclaration.setProperty() API, CSSOM, Method, Reference
The CSSStyleDeclaration.setProperty() method interface sets a new value for a property on a CSS style declaration object.
359 CSSStyleRule API, CSSOM, Interface, Reference
CSSStyleRule represents a single CSS style rule. It implements the CSSRule interface with a type value of 1 (CSSRule.STYLE_RULE).
360 CSSStyleRule.selectorText API, CSSOM, CSSStyleRule, NeedsSpecTable, Reference
The CSSRule.selectorText property gets the textual representation of the selector for the rule set. This is readonly in some browsers; to set stylesheet rules dynamically cross-browser, see Using dynamic styling information.
361 CSSStyleRule.style API, CSSOM, NeedsSpecTable, Property, Reference
The CSSRule.style property is the CSSStyleDeclaration interface for the declaration block of the CSSRule.
362 CSSStyleSheet API, CSSOM, Reference
The CSSStyleSheet interface represents a single CSS style sheet. It inherits properties and methods from its parent, StyleSheet.
363 CSSStyleSheet.deleteRule() API, CSSOM, CSSStyleSheet, Method, Reference
The CSSStyleSheet.deleteRule() method removes a style rule from the current style sheet object.
364 CSSStyleSheet.insertRule() API, CSSOM, CSSStyleSheet, Method, NeedsMarkupWork, Reference
CSSStyleSheet.insertRule() method inserts a new CSS rule into the current style sheet, with some restrictions.
365 CSSSupportsRule API, CSSOM, Interface, Reference
The CSSSupportsRule interface describes an object representing a single CSS @supports at-rule. It implements the CSSConditionRule interface, and therefore the CSSRule and CSSGroupingRule interfaces with a type value of 12 (CSSRule.SUPPORTS_RULE).
366 CSSValue API, CSSValue, DOM, Interface, NeedsExample, Reference
The CSSValue interface represents the current computed value of a CSS property.
367 CSSValue.cssText API, CSSValue, Property, Reference, cssText
The cssText property of the CSSValue interface represents the current computed CSS property value.
368 CSSValue.cssValueType API, CSSValue, Property, Read-only, Reference, cssValueType
The cssValueType read-only property of the CSSValue interface represents the type of the current computed CSS property value.
369 CSSValueList API, CSSValueList, DOM, Interface, Reference
The CSSValueList interface derives from the CSSValue interface and provides the abstraction of an ordered collection of CSS values.
370 CSSValueList.item() API, CSSValueList, Method, Reference, item
The item() method of the CSSValueList interface is used to retrieve a CSSValue by ordinal index.
371 CSSValueList.length API, CSSValueList, NeedsExample, Property, Read-only, Reference, length
The length read-only property of the CSSValueList interface represents the number of CSSValues in the list. The range of valid values of the indices is 0 to length-1 inclusive.
372 Cache API, Cache, Cache API, Experimental, Interface, Offline, Reference, Service Workers, Service worker API, Storage
The Cache interface provides a storage mechanism for Request / Response object pairs that are cached, for example as part of the ServiceWorker life cycle. Note that the Cache interface is exposed to windowed scopes as well as workers. You don't have to use it in conjunction with service workers, even though it is defined in the service worker spec.
373 Cache.add() API, Cache, Experimental, Method, Reference, Service Workers, Service worker API, ServiceWorker
The add() method of the Cache interface takes a URL, retrieves it, and adds the resulting response object to the given cache. 
374 Cache.addAll() API, Cache, Experimental, Method, NeedsExample, Reference, Service Workers, Service worker API, ServiceWorker, addAll
The addAll() method of the Cache interface takes an array of URLs, retrieves them, and adds the resulting response objects to the given cache. The request objects created during retrieval become keys to the stored response operations. 
375 Cache.delete() API, Cache, Experimental, Method, NeedsContent, NeedsExample, Reference, Service Workers, ServiceWorker, delete
The delete() method of the Cache interface finds the Cache entry whose key is the request, and if found, deletes the Cache entry and returns a Promise that resolves to true. If no Cache entry is found, it returns false.
376 Cache.keys() API, Cache, Experimental, Method, Reference, Service Workers, ServiceWorker, keys
The keys() method of the Cache interface returns a Promise that resolves to an array of Cache keys.
377 Cache.match() API, Cache, Experimental, Method, Reference, Service Workers, Service worker API, ServiceWorker, match
The match() method of the Cache interface returns a Promise that resolves to the Response associated with the first matching request in the Cache object. If no match is found, the Promise resolves to undefined.
378 Cache.matchAll() API, Cache, Experimental, Method, Reference, Service Workers, ServiceWorker, matchAll
The matchAll() method of the Cache interface returns a Promise that resolves to an array of all matching requests in the Cache object.
379 Cache.put() API, Cache, Experimental, Method, NeedsExample, Reference, Service Workers, Service worker API, ServiceWorker, put
The put() method of the Cache interface allows key/value pairs to be added to the current Cache object.
380 CacheStorage API, CacheStorage, Experimental, Expérimental(2), Interface, Reference, Référence(2), Service Workers, ServiceWorker
The CacheStorage interface represents the storage for Cache objects.
381 CacheStorage.delete() API, CacheStorage, Experimental, Expérimental(2), Method, Reference, Référence(2), Service Workers, ServiceWorker, delete
The delete() method of the CacheStorage interface finds the Cache object matching the cacheName, and if found, deletes the Cache object and returns a Promise that resolves to true. If no Cache object is found, it returns false.
382 CacheStorage.has() API, CacheStorage, Experimental, Expérimental(2), Method, Reference, Référence(2), Service Workers, ServiceWorker, has
The has() method of the CacheStorage interface returns a Promise that resolves to true if a Cache object matches the cacheName.
383 CacheStorage.keys() API, CacheStorage, Experimental, Method, Reference, Service Workers, Service worker API, ServiceWorker, keys
The keys() method of the CacheStorage interface returns a Promise that will resolve with an array containing strings corresponding to all of the named Cache objects tracked by the CacheStorage object in the order they were created. Use this method to iterate over a list of all Cache objects.
384 CacheStorage.match() API, CacheStorage, Experimental, Method, Reference, Service Workers, Service worker API, ServiceWorker, match
The match() method of the CacheStorage interface (available globally as caches) checks if a given Request or url string is a key for a stored Response. This method returns a Promise for a Response, or undefined if no match is found.
385 CacheStorage.open() API, CacheStorage, Experimental, Method, Reference, Service Workers, Service worker API, ServiceWorker, open
The open() method of the CacheStorage interface returns a Promise that resolves to the Cache object matching the cacheName.
386 Canvas API API, Canvas, JavaScript, Overview, Reference
Added in HTML5, the HTML <canvas> element can be used to draw graphics via scripting in JavaScript. For example, it can be used to draw graphs, make photo compositions, create animations, or even do real-time video processing or rendering.
387 A basic ray-caster Advanced, Canvas, Example, Graphics, HTML, Web

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